What is Hadrian's wall purpose?

Answer 1

To keep the Scottish tribes, who were considered "savages," from raiding England.

Answer 2

The Romans used fortified walls or a series of forts to make it hard for their uncivilized neighbors to mount large-scale raids into Roman territory. It was hard enough to pacify the unruly southern 2/3 of England, and the Roman military was getting stretched too thin to do the expensive and difficult task of conquering the Picts up north into what is now Scotland, so Hadrian had a wall built across a conveniently narrow bit of England to try to keep the Pictish hillbillies from their standard recreational lootage and pillage of the Romanized British settlements. It was never perfectly successful at keeping them out, but at least it kept things from getting too far out of hand before the local garrisons could come up and boot them back into their mountains.

Answer 3

to block the view into his yard by his nosey neighbor